Flexible catheters are used for percutaneous drainage of an abscess or pocket of fluid in the body to the exterior by means of gravity or negative pressure. Fluid collection may be the result of an infection, surgery, trauma or other causes. Typical fluids include biliary, nephrostomy, pleural, urinary, and mediastinal collections. As an alternative to providing drainage, these catheters can also be used to introduce substances, such as fluids, into a patient's body.
In percutaneous drainage procedures, a catheter is typically introduced into a patient through a hypodermic needle or a trocar. A guidewire is inserted through the needle, which is then removed. The catheter tube, with a stiffening cannula, then passes over the previously emplaced guide wire into the drainage site in the body cavity. The stiffening cannula is then removed.
Once a drainage catheter is in position in the body cavity, it is desirable to anchor the catheter before drainage begins. Typically, this can be done by forming a restraining portion in the distal end of the catheter in the form of a pigtail or “J-curve.” For a pigtail configuration, a flexible tension member, such as a suture thread, extends through draw ports at two spaced positions along the distal portion of the catheter. The restraining portion is conventionally activated by manually pulling the suture thread so that the two draw ports move toward each other as the pigtail loop forms at the distal end of the catheter. When the suture thread is taut, it prevents the pigtail loop from straightening by holding the juxtaposed portions of the catheter together in a locked position. The restraining portion is thus in a shape capable of resisting displacement from the body cavity. Once actuated, this restraining portion prevents removal of the catheter. When the catheter is ready to be removed, the cannula is inserted through the lumen until it reaches the pigtail loop. The restraining portion at the distal end is unlocked by cutting or releasing the suture at the proximal end, where the catheter protrudes from the body.
A preformed curve in the shape of a malecot rib has also been used as a possible anchoring mechanism. In this configuration, longitudinal slits are located in the restraining portion of the catheter at the distal end. The rib is activated in a similar manner as the pigtail configuration by manipulating a tension member, except the restraining portion is formed in the shape of multiple wings (typically two or four) instead of a pigtail.
Successful procedures involving percutaneous drainage depend upon the initial placement of the drainage catheter and having the catheter remain in place for the duration of the treatment. Without adequate anchoring or support, catheter dislodgment may result due to body movements by the patient or under other conditions.
Described herein are unique devices, systems and methods for supplementing the pigtail or malecot anchoring mechanism by using a catheter that is configured to naturally form a pigtail curve upon manipulation of a stylet or a control wire.